This invention relates to electronic communication systems and more particularly to web browsing and browsers in such systems.
Web browsing using mobile phones is limited by several factors, including screen size, input device, connection speed, and subscription rate (e.g., flat-rate charging vs. per-kilobyte charging). Some handset vendors, most notably Apple Inc., Cupertino, Calif., USA, for its iPhone cellular telephone, provide a standard web browser, while other handset vendors provide mobile versions of other web browsers that account for, in particular, the limited form factor of handsets.
From a handset user's perspective, some web pages may be hard to interact with using a standard or downscaled web browser because of assumptions made by the web page designers about the viewing area that will be available. For example, it may have been assumed that the viewing area would be at least 800×600 pixels or 1400×1050 pixels. Buttons and dialog boxes positioned and sized for such viewing areas can be difficult to translate to viewing areas of 320×320 pixels and the like that are typical of handsets. Furthermore, for a handset user paying for content by the megabyte or saddled with a low-bandwidth connection, some pages impose such high penalties in cost or download time that the user is discouraged from viewing them.
One approach to reducing the limitations of handheld web browsing is to interpose a proxy server in the chain between the handset and the content server. The proxy server preprocesses pages requested by a handset, for example by replacing the original requested page by a dynamically generated replacement page that is reformatted to better suit the mobile web browser. Operations such as downscaling of images to reduce bandwidth use may be performed in the proxy as part of its preprocessing. This approach is taken by, for example, Opera Software ASA, Oslo, Norway.
This and other approaches to adapting, or translating, web content to accommodate the limitations of mobile devices, such as cellular telephone handsets, are described in the literature.
T.-Y. Chang et al., “Cut-Load: Application-Unaware Content Partitioning for Web-based Information Access in Wireless Data Networks”, IEEE International Conference on Communications, vol. 1, pp. 409-416 (June 2006) describes a content-translating proxy for adapting web content to mobile devices, in which the decision to translate is based on several factors, such as thin-friendliness, size of content, and network conditions. In a “normal” mode, the client application operates as a normal web client, and in a “dual” mode, the client initially operates in a “thin” mode while processing requested content in the background. Chang's system of “graphical content partitioning” automatically divides requested content into several smaller pieces that can be downloaded one at a time. If an entire large page is downloaded, the overhead of the partitioning results in a larger bandwidth requirement than the original page, and so Chang implements “dynamic mode selection” based on network signal-to-noise ratio and a “body-mass index” (BMI) of the requested document, which is defined as the document's size in bytes divided by the square of the page size in pixels.) Depending on the result of this test, the partitioned or the original page is transmitted.
International Publication WO 01/86462 describes a proxy server for translating web content (e.g., pages written in hypertext markup language (HTML) and or extensible markup language (XML)) for mobile devices, such as cellular phones. Translation is done according to user preferences that are transferred to the proxy server and stored in a database, but no ability to translate or not is disclosed.
Y. Chen et al., “Adapting Web Pages for Small-Screen Devices”, Internet Computing, vol. 9, no. 1, pp. 50-56, IEEE Computing Society (2005); and T. Laakko et al., “Adapting Web Content to Mobile User Agents”, Internet Computing, vol. 9, no. 2, pp. 46-53, IEEE Computer Society (2005) relate to proxy adaptation for mobile web browsing, including algorithms for translating web pages, but no ability to translate or not is disclosed.
U.S. Pat. No. 6,535,922 describes a system for adapting Internet data, such as web pages, to portable/handheld computers that have limited capabilities for processing, power, screen size, and screen resolution. A web server capable of translating HTML data communicates requested pages to the portable device, which can transfer specific characteristics, such as screen size and resolution, to the server so that the server can adapt the requested pages before serving them to the portable device.
J. González et al., “Multi-Format Web Content Transcoding for Mobile Devices”, Seventh Mexican International Conference on Computer Science (ENC '06), pp. 109-115, IEEE (2006) describes adaptation using a client-side proxy and a server-side proxy, including transcoding (i.e., translating) web pages based on an extensible stylesheet language (XSL) description provided by the client. The client informs the server of its requirements on the web page.
U.S. Pat. No. 6,374,305 describes a mobile browser that is able to use conventional web-based applications by using two specialized software layers: a proxy layer on the mobile device and a web agent on the server.
Even with a preprocessing proxy server, however, some pages simply will not be displayed properly on all of the wide variety of handsets that are commercially available. Problems are typically encountered with pages that include dynamic HTML or asynchronous JavaScript and XML (AJAX), and secure pages delivered over secure sockets layer (SSL). As a result, users are forced to have two or more separate browsers installed on the handsets, and to switch between the browsers according to the pages requested.